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Are the fragments that are generated made of up small squares as shown in the slide? If so, why? Wouldn't using triangles offer better accuracy for rendering an image?


@captianFlint, the little square is just a representation. A fragment corresponds to a pixel in the image, and it will be rendered as the pixel after passing some tests such as depth test and alpha blending. so I guess the main reason for fragments to be little squares is that we like to represent image pixels as little squares, which is not a very precise representation ;-)


What sort of things can be primitives outside of the examples given (triangles, points, and lines)? Can any polygon be a primitive?


@jaguar, yes, GL_POLYGON can be taken as parameter for gl_Begin(). Also you can consider quadrilaterals as primitives as implied by GL_QUAD.



There are also some really exotic primitives like GL_LINE_LOOP and GL_TRIANGLE_FAN. Here is a nice illustration:

In practice, triangles are used most often, though some subdivision algorithms use quads.